Brian, no need to take the spring out to fix the problem. check the fitting on top of the spring, one is a zerk the other is a relief. Grease will leak out of them if not tight. Put the bolts back in the spring hold down.Grease will leak inside of the spring if the seal are out of the hydro adjuster, if that is the case the seal are out of the hydro adjuster. Inside of the spring on the idler side (front) is a chrome cylinder, in the cylinder are the seals that are leaking. Take a block of wood put in the spocket, loosen the relif on the top of the spring, back the tractor up, force the cylinder back into the spring all the way. The shaft that bolts to the cylinder is connected ot the front idler,unbolt the shaft at the cylinder pull the idler forward,inside of the cylinder are the seals and piston. Pull the piston out of the cylinder, the new seal installed lip forward. I think you have a 8u or 9u D6, look on the back left corner of the dozer for the serial number you will need that when you order . TROLL